Many industries use drills to cut holes in components to be assembled into products. The aircraft industry is a prime example of an industry that uses many drills of various sizes to cut holes in a variety of components formed of various metals (e.g., aluminum and titanium) and synthetic materials (e.g., fiber reinforced resin composites).
In order to maintain their ability to cut accurately and quickly, drills must be frequently refurbished, i.e., sharpened and cleaned of the grit and debris that accumulates in the flutes of the drill. During refurbishing, drills are sized both for sorting and to determine if the drills are debris free.
In the past, drills have been sized by inserting them by hand into bushings that gauge the drill diameter. The process must be performed twice for step drills, i.e., drills that include a small diameter pilot section and a major diameter section. Like most manual operations, accurate drill sizing varies from person to person because it depends on the sizer's "feel" and the bushing condition. Manual sizing becomes most difficult when large numbers of drills separated by small amounts are to be sized. In addition to being undesirable from an accuracy point of view, manual sizing is expensive, particularly when it is necessary to size a large number of drills per week. The aircraft company that is the assignee of this application frequently sizes 50,000 or more drills per week.
One proposal to mechanize the refurbishing and sorting of drills is described in U.S. Pat. No. 4,380,295 entitled "Automatic Drill Deburring and Sorting Machine" by Mark S. Soderberg et al., assigned to the assignee of the present application. While the drill deburring and sorting machine described in this patent overcomes some of the disadvantages of the manual system described above, the machine has certain limitations. For example, it is directed to measuring and sorting special types of drills--quick change drills. It is not designed for use with general purpose drills. Nor is it designed for use with step drills. While step drills, like general purpose drills, can be sized for major diameter, the machine provides no information on the step size. Further, the machine is slower than desired.
This invention is directed to providing a drill diameter measuring machine that is more versatile. More specifically, this invention is directed to providing a drill diameter measuring machine that provides both major and step drill diameter information in one machine cycle and that will accept a wide variety of drill types, including long and short quick change drills, straight shank drills and threaded adapted drills.